In recent years, a chair in which a leg column for supporting a seat body is tiltably supported by an installation base has been proposed (see, for example, Patent Documents 1, 2 and 3).
In the chair described in Patent Document 1, an accommodating chamber for accommodating a rubber-like elastic member is provided on the installation base, and the rubber-like elastic member is fixed to a lower end of the leg column and is accommodated in the accommodating chamber. A gap which allows swelling of the elastic member is provided in the accommodating chamber. In this chair, as the rubber-like elastic member swells outward through the gap, deformation of the elastic member itself and associated tilting of the leg column are permitted. At this time, an elastic reaction force of the elastic member acts on the leg column.
In the chair described in Patent Document 2, a flange-like abutting wall is provided at a lower end of the leg column, and a rubber-like elastic member and an auxiliary reaction force generating member such as a coil spring are interposed in parallel between the abutting wall and the installation base. In this chair, as the rubber-like elastic member and the auxiliary reaction force generating member are elastically deformed, the tilting of the leg column is permitted, and the reaction force of the elastic member and the auxiliary reaction force generating member acts on the leg column.
In the chair described in Patent Document 3, a lower end of the leg column is tiltably supported on the installation base via a rubber-like elastic member. A support wall for supporting a lower surface of the elastic member is provided on the installation base, and an abutting wall for supporting an upper surface of the elastic member is provided on the leg column. The elastic member is sandwiched in a compressed state between the abutting wall of the leg column and the support wall of the installation base. Further, a tilting allowance hole through which a lower part of the leg column is tiltably inserted is provided in the installation base, and the abutting wall and the elastic member are disposed inside the tilting allowance hole. When the leg column tilts, the abutting wall tilts together with the leg column to deform the elastic member.
Furthermore, in the chair described in Patent Document 1, the lower part of the leg column is supported by the installation base via the rubber-like elastic member, and a tilting allowance hole through which the lower part of the leg column is tiltably inserted is provided in the installation base. An abutting wall which comes into contact with an upper surface of the elastic member is provided on a leg portion, and an inward flange portion is provided on an inner peripheral edge portion of the tilting allowance hole of the installation base to cover an upper part of a peripheral edge portion of the abutting wall.